Injection molding is a manufacturing process used to make polymeric articles. In its simplest form, a polymer is heated to a molten state and forced into a mold cavity where the polymer cools and hardens. The mold is then opened and the part removed.
Reaction injection molding (RIM) is a specific type of injection molding where the liquid introduced into the mold contains chemicals which react to form the polymer instead of the molten polymer itself being injected into the mold. A specific example of RIM is the introduction of an isocyanate and polyol which react in the mold to form a polyurethane. RIM presents special challenges in the injection molding process. Since the components are reactive and polymerize in the mold, it can be difficult for the part to be removed from the mold. The adhesion of the polymer to the metal surface can reduce the lifetime of molds, degrade the quality of the replication, and complicate the processing procedure. Increased time for the molding process, increased costs due to more frequent cleaning, and defective parts caused by poor release from the mold surface are examples of challenges from poor release. For these reasons, metal molds are often coated with a release agent in order to overcome the adhesion of the polymeric part to the metal surface.
Thermoforming is another manufacturing process that is used to make polymeric materials. In the thermoforming process, a plastic sheet or film is heated until it is pliable and is then formed into a desired shape in a mold. For example, a plastic sheet can be heated and then stretched into or onto a mold, cooled for a finished shape, and then trimmed to create the end product. Release of formed plastic parts from thermoforming molds can also be challenging. Thermoforming molds, like injection molding molds, are therefore often coated with release agents.